1. Field of the Invention
The present invention is directed to a device and method especially useful in the insertion of medical devices in the right ventricle of the heart. The invention provides a novel and improved introducer sheath useful in placement of a ventricular pacing lead at the apex of the right ventricle for permanent pacemaker implantation. The present invention also relates to an improved dilator for use with the introducer sheath.
2. Prior Art
Development of permanent implantable pacemaker systems has resulted in life-saving benefits and has greatly improved the quality of life of patients with symptomatic bradyarrhythmias. There are single chamber ventricular pacing methods and dual chamber atrial-ventricular pacing methods. The benefits of dual chamber pacing compared to single chamber ventricular pacing are well documented. Most dual chamber pacing systems use separate atrial and ventricular pacing leads. Permanent pacemaker systems also have been developed which maintain atrial-ventricular synchrony using only a single permanent pacing lead. Such systems are only applicable to specific patient subpopulations. Single chamber atrial pacing is rarely appropriate. Therefore, nearly all patients who undergo permanent pacemaker implantation require ventricular pacing lead placement.
Techniques currently in use for permanent pacemaker implantation typically obtain venous access by one of two methods. A mid infraclavicular incision is made in the skin on either the left or right side of the patient. The left or right subclavian vein is punctured with a thin-walled, large-bore needle and a guidewire is passed into the vein. The needle is removed and an introducer sheath is advanced over the wire with the aid of a dilator into the subclavian vein. After the introducer sheath is in the subclavian vein, the dilator is withdrawn. The pacemaker lead is passed into the venous circulation system through the introducer sheath. The guidewire may be removed or may be left in place as the pacing lead is passed through the system. Current introducer sheaths are only of sufficient length to ensure access to the subclavian vein and, in some patients, to the superior vena cava. Alternatively, a pacemaker lead can be introduced by isolating the cephalic vein and introducing the lead under direct visualization via a venotomy. Regardless of the technique used to obtain venous access, the pacemaker lead must then be advanced via the superior vena cava into the right atrium and then manipulated across the tricuspid valve into the right ventricle and then further advanced past ventricular trabeculae to the apex of the right ventricle for optimal pacing location.
The range of ventricular lead placement devices available for cardiologists and surgeons today are often cumbersome and time consuming to use, especially for cardiologists and surgeons with low annual volumes of pacemaker implantations (i.e. less than 75 pacemaker implants per year). Cardiologists and surgeons frequently have trouble passing the ventricular pacing lead across the tricuspid valve to the apex of the right ventricle because of the interaction of the lead tines or active fixation apparatus with the tricuspid valve or with right ventricle trabeculae. Additionally, the ventricular pacing lead may be inadvertently passed into the coronary sinus. These problems result in increased blood loss and increased radiation exposure for the physician, assistants, and patient.
The present invention is designed to eliminate the problems associated with passing the ventricular pacing lead through the tricuspid valve and past the ventricular trabeculae, prevent inadvertent passing of the pacing lead into the coronary sinus, reduce blood loss, and reduce radiation exposure for the physician, assistants, and patient.
Pacemaker leads are very soft and flexible, thus not easily guided and manipulated into the proper location. Therefore, it is common to use straight and curved stylets to temporarily stiffen the pacing lead and provide directional control to facilitate manipulation of the pacing lead from the right atrium across the tricuspid valve into the right ventricle. Typically, a straight stylet is used to initially introduce the lead into the right atrium. Then the straight stylet is removed and a curved stylet is used to advance the pacing lead across the tricuspid valve into the right ventricle. It is common practice to use the curved stylet to advance the pacing lead past the right ventricle into the right ventricle outflow tract or pulmonary artery to ensure that the pacing lead is not in the coronary sinus. Often times, the curved stylet must be removed and re-shaped during the procedure to attain adequate manipulation and positioning. Then the pacing lead is withdrawn from the right ventricle outflow tract or pulmonary artery using a straight stylet to allow the pacing lead to descend into the apex of the right ventricle for fixation of the pacing lead at the apex with the tines or the active fixation mechanism. Since the coronary sinus does not communicate with the right ventricle outflow tract or pulmonary artery, this technique helps to ensure that the pacing lead is in the right ventricle instead of the coronary sinus. The lead placement procedure is done under fluoroscopy to enable proper pacing lead placement.
The standard method for ventricular pacing lead placement requires extensive lead manipulation, multiple stylet exchanges, and multiple stylet reshapings. In addition, the standard method has potential for inappropriate lead positioning in the coronary sinus and exposing the physician, nurses, and patient to excessive radiation due to the extended use of fluoroscopy.
U.S. Pat. No. 4,243,050 to Littleford discloses a conventional introducer, introducer sleeve and method for implanting pacemaker electrodes in a patient. The introducer and introducer sleeve are dimensioned to only reach into the subclavian vein. Stylets are used inside of the pacing lead in order to advance the lead through the venous system to the apex of the right ventricle.
U.S. Pat. No. 4,467,817 to Harris discloses a small diameter pacing lead of carbon filaments surrounded by a stiffening sheath. The tip of the pacing lead extends beyond the stiffening sheath whereby the stiffening sheath is positioned behind the tip of the pacing lead to assist guiding the pacing lead into the desired organ.
European Patent Application No. 219,608 of Osypka discloses a pacing lead enclosed by a guide sleeve. The guide sleeve is a protective coating that extends over the attaching end of the pacing lead. The guide sleeve has a longitudinal tear line along its length so that it may be separated as it is retracted from the pacing lead.
U.S. Pat. No. 4,602,645 to Barrington et al. discloses a cardiac pacing catheter system used for temporary placement of pacing leads for atrio-ventricular pacing. A standard length introducer sleeve is used to introduce the cardiac pacing catheter system into the subclavian vein. The catheter containing the pacing leads is advanced through the superior vena cava to the entry to the right atrium and then secured in place. Then the ventricular lead is extended into and through the right atrium, through the tricuspid valve and into the right ventricle. Subsequently, the atrial lead is extended into the right atrium.
U.S. Pat. No. 5,246,014 to Williams et al. discloses a complex implantable active fixation lead system consisting of an active fixation pacing lead, an introducer having a coupler which engages a crank portion on the active fixation pacing lead, and a guide catheter that is assembled with the pacing lead and the introducer for imparting stiffness and improved steerability to the pacing lead. The implantable active fixation lead system is inserted through the subclavian vein into the superior vena cava and into the right ventricle through the tricuspid valve. The introducer and active fixation pacing lead are extended past the guide catheter in the area of the right ventricle apex. The active fixation pacing lead is then cranked into the cardiac tissue by rotating the introducer.
In view of the limitations and complexities of the prior art devices, it would be highly desirable to have an apparatus and method that would facilitate simple, rapid permanent pacemaker ventricular pacing lead placement requiring little or no lead manipulation, eliminate the need for multiple stylets, and decrease the risk of inappropriate lead placement.